Pros

Pro

Seamless autofill and password generator via plugins for all popular browsers

All common browsers, including Opera, have plugins that allow automatically filling in forms and generating passwords. All form fill information syncs across all platforms, devices and browsers. Password generator can be adjusted to use or exclude certain characters and patterns.

Pro

Automatic cloud backup and cross-device sync

LastPass keeps an encrypted copy of all passwords locally as well as an encrypted copy on their servers. That way, passwords can be accessed locally while offline, or through their server while online from any machine.

Pro

Works with portable versions of Chrome and Firefox

Firefox 2+ on Windows, Mac & Linux as well as Chrome 4+ on Windows and Linux support a portable version of LastPass. Great for securely accessing LastPass Vault from public or untrusted computers.

Pro

Works on Linux

LastPass alongside KeePassX are the only cloud-syncing password managers that work on Linux.

Pro

All encryption and decryption is done locally

All the encryption and decryption is done by the client (JS/App) so even LastPass doesn't have access to passwords.

Pro

Does not require a standalone app

While many password managers require a standalone app to be installed on the system, LastPass does not and can function via browser plugins.

Pro

Allows sharing passwords with one person or a group of people

LastPass allows sharing login data for a site with another user of LastPass without exposing the password. Great for allowing friends, family or coworkers access a site.

Pro

Offers multiple export options

LastPass can dump the whole database as a .csv file or an encrypted file that can then be decrypted using LastPass Pocket as well as separately export Wi-Fi passwords and autofill information. Additional export options are available on a per-browser basis.

Pro

Fingerprint verification

Some fingerprint readers, like TouchID on iOS devices, can be set up to be used to access LastPass instead of a master password.

Pro

Can create one-time passwords for accessing the Vault

LastPass allows creating passwords for accessing the LastPass Vault that can only be used once. Great for accessing the Vault in public or untrusted places.

Pro

Yubikey Support

Pro

Allows downloading an encrypted database backup that can only be decrypted with LastPass Pocket

LastPass Pocket is a standalone personal database decrypter. It's a portable executable, meaning it does not need to be installed, that is used to decrypt a local encrypted copy of the password database.

Pro

Military grade encryption

Pro

Credit monitoring in US

LastPass can be set to notify if a user's credit report suddenly changes.

Pro

Vetted by Steve Gibson

Steve Gibson is a well established security researcher best know for his work with Apple and Atari systems as well as founding Gibson Research Corporation. He was given access to LastPass' source code and confirmed that it's safe to trust its security.

Pro

Works even with browsers that don't support plugins

Via a clever use of bookmarklets, LastPass works on browsers that don't inherently support bookmarklets, like Opera or Safari on iOS.

Pro

Offers their own browser on iOS

LastPass offers a browser for iOS with LastPass functionality specifically to circumvent the lack of plugin support on Safari.

Cons

Con

The service has security issues

On Jun 15, 2015 LastPass issued a statement that attackers gained access to their system and got their hands on hashed master passwords.

Con

Forced cloud backup

The is no way to opt-out of saving all of passwords on LastPass servers.

Con

Not free/libre

This application is proprietary, and thus cannot be modified, freely distributed, or trusted to be secure.

Con

Has no menubar app or standalone application

Con

History of bad support for the company behind LastPass

You never know how much you will pay for it because LogMeIn did the same with Hamachi product. Support will be bad.

Con

When generating passwords, LastPass tends to put the wrong info in forms

For forms with both an email address and username, LastPass tends to mix up and overwrite information.

Con

Somewhat poor customer service

Con

Forgets to ask "add new site?" on some websites

So you are forced to add a new site manually, which takes too long (relatively speaking).